#!/bin/bash
# Version: 1.0.5
# ==============================================================================
# SAP HANA Backup Script
#
# Performs schema exports for one or more schemas and/or tenant backups for a
# SAP HANA database. Designed to be executed via a cronjob.
# Reads all settings from the backup.conf file in the same directory.
# ==============================================================================

# --- Configuration and Setup ---

# Find the script's own directory to locate the config file
SCRIPT_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" &> /dev/null && pwd)
CONFIG_FILE="${SCRIPT_DIR}/backup.conf"

# Check for config file and source it
if [[ -f "$CONFIG_FILE" ]]; then
    source "$CONFIG_FILE"
else
    echo "❌ Error: Configuration file not found at '${CONFIG_FILE}'"
    exit 1
fi

# Check if hdbsql executable exists
if [[ ! -x "$HDBSQL_PATH" ]]; then
    echo "❌ Error: hdbsql not found or not executable at '${HDBSQL_PATH}'"
    exit 1
fi

# Calculate threads to use (half of the available cores, but at least 1)
TOTAL_THREADS=$(nproc --all)
THREADS=$((TOTAL_THREADS / 2))
if [[ "$THREADS" -eq 0 ]]; then
    THREADS=1
fi

# --- Functions ---

# Performs a binary export of a specific schema.
# Accepts the schema name as its first argument.
perform_schema_export() {
    local schema_name="$1"
    if [[ -z "$schema_name" ]]; then
        echo "   ❌ Error: No schema name provided to perform_schema_export function."
        return 1
    fi

    echo "⬇️  Starting schema export for '${schema_name}'..."

    local timestamp
    timestamp=$(date +%Y%m%d_%H%M%S)
    local export_base_dir="${BACKUP_BASE_DIR}/schema"
    local export_path="${export_base_dir}/${schema_name}_${timestamp}"
    local query_export_path="$export_path"

    if [[ "$COMPRESS_SCHEMA" == "true" ]]; then
        export_path="${export_base_dir}/tmp/${schema_name}_${timestamp}"
        query_export_path="$export_path"
        echo "   ℹ️ Compression enabled. Using temporary export path: ${export_path}"
    fi

    local archive_file="${export_base_dir}/${schema_name}_${timestamp}.tar.gz"

    mkdir -p "$(dirname "$export_path")"

    local query="EXPORT \"${schema_name}\".\"*\" AS BINARY INTO '${query_export_path}' WITH REPLACE THREADS ${THREADS};"

    "$HDBSQL_PATH" -U "$USER_KEY" "$query" > /dev/null 2>&1
    local exit_code=$?

    if [[ "$exit_code" -eq 0 ]]; then
        echo "   ✅ Successfully exported schema '${schema_name}'."

        if [[ "$COMPRESS_SCHEMA" == "true" ]]; then
            echo "   🗜️  Compressing exported files..."
            tar -czf "$archive_file" -C "$(dirname "$export_path")" "$(basename "$export_path")"
            local tar_exit_code=$?

            if [[ "$tar_exit_code" -eq 0 ]]; then
                echo "   ✅ Successfully created archive '${archive_file}'."
                echo "   🧹 Cleaning up temporary directory..."
                rm -rf "$export_path"
                rmdir --ignore-fail-on-non-empty "$(dirname "$export_path")"
                echo "   ✨ Cleanup complete."
            else
                echo "   ❌ Error: Failed to compress '${export_path}'."
            fi
        else
            echo "   ℹ️ Compression disabled. Raw export files are located at '${export_path}'."
        fi
    else
        echo "   ❌ Error: Failed to export schema '${schema_name}' (hdbsql exit code: ${exit_code})."
    fi
}

# Loops through the schemas in the config file and runs an export for each.
run_all_schema_exports() {
    if [[ -z "$SCHEMA_NAMES" ]]; then
        echo "   ⚠️  Warning: SCHEMA_NAMES variable is not set in config. Skipping schema export."
        return
    fi

    echo "🔎 Found schemas to export: ${SCHEMA_NAMES}"
    for schema in $SCHEMA_NAMES; do
        perform_schema_export "$schema"
        echo "--------------------------------------------------"
    done
}

# REFACTORED: Generic function to back up any database (Tenant or SYSTEMDB).
# Arguments: 1:Backup Name (for logging), 2:User Key, 3:Base Directory, 4:Compression Flag
perform_database_backup() {
    local backup_name="$1"
    local user_key="$2"
    local backup_base_dir="$3"
    local compress_enabled="$4"

    echo "⬇️  Starting ${backup_name} backup..."

    local timestamp
    timestamp=$(date +%Y%m%d_%H%M%S)
    local backup_path_prefix
    local backup_target_dir

    if [[ "$compress_enabled" == "true" ]]; then
        backup_target_dir="${backup_base_dir}/tmp"
        backup_path_prefix="${backup_target_dir}/backup_${timestamp}"
        echo "   ℹ️ Compression enabled. Using temporary backup path: ${backup_path_prefix}"
    else
        backup_target_dir="$backup_base_dir"
        backup_path_prefix="${backup_target_dir}/backup_${timestamp}"
    fi

    mkdir -p "$backup_target_dir"

    local query="BACKUP DATA USING FILE ('${backup_path_prefix}')"

    "$HDBSQL_PATH" -U "$user_key" "$query" > /dev/null 2>&1
    local exit_code=$?

    if [[ "$exit_code" -eq 0 ]]; then
        echo "   ✅ Successfully initiated ${backup_name} backup with prefix '${backup_path_prefix}'."

        if [[ "$compress_enabled" == "true" ]]; then
            local archive_file="${backup_base_dir}/backup_${timestamp}.tar.gz"
            echo "   🗜️  Compressing backup files..."
            tar -czf "$archive_file" -C "$backup_target_dir" .
            local tar_exit_code=$?

            if [[ "$tar_exit_code" -eq 0 ]]; then
                echo "   ✅ Successfully created archive '${archive_file}'."
                echo "   🧹 Cleaning up temporary directory..."
                rm -rf "$backup_target_dir"
                echo "   ✨ Cleanup complete."
            else
                echo "   ❌ Error: Failed to compress backup files in '${backup_target_dir}'."
            fi
        fi
    else
        echo "   ❌ Error: Failed to initiate ${backup_name} backup (hdbsql exit code: ${exit_code})."
    fi
}

# --- Main Execution ---

echo "⚙️  Starting HANA backup process..."

mkdir -p "$BACKUP_BASE_DIR"

case "$BACKUP_TYPE" in
    schema)
        run_all_schema_exports
        ;;
    tenant)
        perform_database_backup "Tenant" "$USER_KEY" "${BACKUP_BASE_DIR}/tenant" "$COMPRESS_TENANT"
        ;;
    all)
        run_all_schema_exports
        perform_database_backup "Tenant" "$USER_KEY" "${BACKUP_BASE_DIR}/tenant" "$COMPRESS_TENANT"
        ;;
    *)
        echo "   ❌ Error: Invalid BACKUP_TYPE '${BACKUP_TYPE}' in config. Use 'schema', 'tenant', or 'all'."
        ;;
esac

# NEW: Check if SYSTEMDB backup is enabled, regardless of BACKUP_TYPE (as long as it's not 'schema' only)
if [[ "$BACKUP_TYPE" == "tenant" || "$BACKUP_TYPE" == "all" ]]; then
    if [[ "$BACKUP_SYSTEMDB" == "true" ]]; then
        echo "--------------------------------------------------"
        if [[ -z "$SYSTEMDB_USER_KEY" ]]; then
            echo "   ❌ Error: BACKUP_SYSTEMDB is true, but SYSTEMDB_USER_KEY is not set in config."
        else
            perform_database_backup "SYSTEMDB" "$SYSTEMDB_USER_KEY" "${BACKUP_BASE_DIR}/systemdb" "$COMPRESS_TENANT"
        fi
    fi
fi

echo "📦 Backup process complete."
echo "👋 Exiting."